1. Technical Field
The field of this invention is anastomosis and anastomotic devices.
2. Background of the Invention
The human body has numerous vessels carrying fluid to essential tissues and areas for recirculation or excretion. When vessels become damaged, severed or wholly occluded due to physiological problems, certain sections must be bypassed to allow for the free and continuous flow of fluids. Anastomosis is performed for the purpose of connecting different conduits together to optimize or redirect flow. In cardiac surgery, anastomosis is done to bypass the occluded vessel by harvesting a member of an unobstructed vessel and joining it to the occluded vessel below the point of stenosis.
The common procedure for performing the anastomosis during bypass surgery requires the use of very small sutures, loupes and microsurgical techniques. Surgeons must delicately sew the vessels together being careful not to suture too tightly so as to tear the delicate tissue, thereby injuring the vessel which may then result in poor patency of the anastomosis. Recently, some surgeons have used staples and associated stapling mechanisms and techniques to form an anastomosis, but many of the same difficulties and problems have presented themselves. Basically, the tension and/or compression forces exerted on the vessel walls as a result of suturing and stapling can result in damage to the vessel wall, even to the extent of causing tissue necrosis. Damage to the intima of a vessel is particularly problematic as it may inhibit the natural bonding process that occurs between the anastomized vessels and which is necessary for sufficient patency. Futhermore, damaged vessel walls are likely to have protuberances that when exposed to the bloodstream could obstruct blood flow or may produce turbulence which can lead to formation of thrombus, stenosis and possible occlusion of the artery.
As cardiac surgery is moving into less invasive procedures, surgical access is being reduced, forcing surgeons to work in constantly smaller surgical fields. The procedures are made more difficult due to the multiple characteristics that are unique to each anastomosis and to each patient. For example, the arteries"" internal diameter dimensions are difficult to predict and the inside walls are often covered with deposits of stenotic plaque which creates the risk of dislodging plaque into the patient""s blood stream during the anastomosis procedure. The resulting emboli in turn create a greater risk of stroke for the patient. The dislodgement of plaque is most likely to occur when the vessel wall undergoes trauma such as the puncturing, compression and tension exerted on the vessel by suturing and stapling. The vessel walls can also be friable and easy to tear, and are often covered with layers of fat and/or are deeply seated in the myocardium, adding to the difficulty of effectively and safely performing conventional anastomotic procedures.
Cardiac surgeons sometimes inadvertently suture too loosely, resulting in leakage of fluid from the anastomosis. In addition to creating a surgical field in which it is difficult to see, leakage of fluid from the anastomosis can cause serious drops in blood pressure, acute or chronic. The loss of blood may cause other deleterious effects on the patient""s hemodynamics that may even endanger the patient""s life. In addition, blood loss may induce local scar tissue to develop which often results in further blockage within or damage to the sewn vessel. Furthermore, anastomosing blood vessels may involve risks of physical injury to the patient. For example, when performing coronary artery bypass graffing (CABG) procedures, anastomosis often requires manipulation of the heart, so that surgeons may access the back of the heart as well as the front. When done on a beating heart, this manipulation may result in hemodynamic compromise possibly subjecting the patient to cardiac arrest, particularly during lengthy procedures. In xe2x80x9cstopped heartxe2x80x9d procedures, patients are supported by cardiopulmonary bypass and, thus, risk post-surgical complications (e.g., stroke) that vary directly with the duration for which the heart is under cardioplegic arrest. Consequently, surgeons are constantly searching for techniques to both reduce the risk of tissue damage as well as the laborious and time-consuming task of vessel suturing.
Stapling and coupling procedures have been used in performing large conduit anastomosis. While stapling is successful in gastrointestinal procedures due to the large size and durability of the vessels, as briefly mentioned above, it is less adequate for use in vascular anastomosis. The manufacturing of stapling instruments small enough to be useful for anastomosing smaller vessels, such as coronary arteries, is very difficult and expensive. As stapling instruments are typically made of at least some rigid and fixed components, a stapler of one size will not necessarily work with multiple sizes of vessels. This requires a surgeon to have on hand at least several stapling instruments of varying sizes. This may significantly raise the cost of the equipment and ultimately the cost of the procedure.
When staples are adapted to conform to the smaller sized vessels, they are difficult to maneuver and require a great deal of time, precision, and fine movement to successfully approximate the vessel tissue. Often stapling or coupling devices require the eversion of the vessel walls to provide intima-to-intima contact between the anastomosed vessels. Everting may not always be practical especially for smaller arteries because of the likelihood of tearing when everted. Another factor which may lead to damage or laceration of the vessel and/or leakage at the anastomosis site is the variability of the force that a surgeon may use to fire a stapling instrument causing the possible over- or under-stapling of a vessel. Still other factors include the unintended inversion of the vessel edges and the spacing between staple points. Rectifying a poorly stapled anastomosis is itself a complicated, time-consuming process which can further damage a vessel.
Accordingly, there is a need for an easier, safer and more efficient means for forming anastomotic connections which requires less time and access space than conventional anastomotic procedures.
3. Relevant Literature
U.S. patents of interest include: U.S. Pat. Nos. 6,113,612; 6,113,611; 6,090,136; 6,068,656; 6,068,637; 6,063,114; 6,056,762; 6,036,704; 6,036,703; 6,036,702; 6,030,392; 6,026,814; 6,007,576; 6,007,544; 6,001,123; 5,961,545; 5,948,018; 5,921,995; 5,916,226; 5,904,697; and 4,214,586. Also of interest are the following PCT publications: WO 00/24339; WO 99/65409; WO 99/48427; WO 99/45852; WO 99/08603; WO 98/52474; WO 98/40036; WO 97/31591 and WO 97/31590.